The four-day standoff between al Qaeda-linked terrorists and the Algerian military at a natural gas plant in the remote Sahara desert ended over the weekend with at least 23 hostages dead, including at least one American, out of more than 130 foreigners and several hundred Algerians held hostage by the extremists.

The casualty figures, reported by Algerian state media, are expected to rise.

Algerian officials said special forces killed the 32 heavily armed kidnappers, part of a multinational group of terrorists loyal to the one-eyed Algerian jihadist known as Mokhtar Belmokhtar.

The Algerian military said it recovered heavy machine guns, rocket launchers, missiles and grenades at the site, which they said had been wired with booby-trap bombs. One hostage who spoke to the media during the siege said the Westerners among them were made to wear explosive belts.

As Algerian special forces continue to search the huge plant for survivors and bodies, the death toll “may be revised upward,” Algerian Communications Minister Mohamed Said said Sunday.

Unidentified Algerian officials told reporters that an additional 25 bodies had been found at the plant, though it was not clear whether they were hostages or terrorists.

In Washington on Friday, the State Department identified the dead American as Frederick Buttaccio but gave no further details out of respect for the family’s privacy, spokeswoman Victoria Nuland said.

Other media reports identified Mr. Buttaccio as a Texas resident and said another Texan, Mark Cobb, escaped with Algerian colleagues and contacted his family to say he was safe.

There was no word of the fate, or even the number, of other Americans who were kidnapped.

“We do know that there were Americans there, and we do know that they were held hostage,” Defense Secretary Leon E. Panetta said Saturday before returning to the United States from a European trip.

“As to what has happened [to them], that’s something, frankly, we just need to get better information on.”

In a brief statement from the White House on Saturday evening, President Obama said, “We will remain in close touch with the government of Algeria to gain a fuller understanding of what took place so that we can work together to prevent tragedies like this in the future.”

British Prime Minister David Cameron said Sunday that three British subjects were killed and another three were unaccounted for and feared dead, along with a foreigner who was living in Britain. He said that 22 Britons who survived the ordeal were back in Britain.

“Now, of course, people will ask questions about the Algerian response to these events,” he added, addressing widespread concern about the tactics employed by Algerian special forces.

The Algerian military failed to inform other governments with citizens held captive about their decision to assault the plant Thursday and again Saturday.

Mr. Cameron declined to second-guess Algerian tactics at what he called “one of the most remote places on Earth.”

The sprawling complex is Algeria’s third-largest natural gas facility and is near the desert town of Ain Amenas on Algeria’s border with Libya.

“The responsibility for these deaths lies squarely with the terrorists who launched a vicious and cowardly attack,” Mr. Cameron said.